Biosensor for Field Monitoring of Pesticides in Water

This SBIR Phase II proposal addresses development of a field-portable, amperometric biosensor for monitoring organophosphorus (OP) and carbamate insecticides in water. The miniaturized biosensor will use a modified screen-printed microelectrode with high sensitivity and lowlimit of detection for OP and carbamate pesticides. This biosensor will be selective for OPs and carbamates. The enzyme used to generate the amperometrically detectable species is selectively inhibited by these insecticides, but not by other common classes of agricultural chemicals, such as triazine herbicides. This device is a single use, disposable monitoring chip, since some of the active pesticides, e.g., the OPs, irreversibly inhibit enzyme activity. Carbamate inhibition is more reversible, but the device, in this case, was still evaluated for a single use mode. During Phase I, we demonstrated effective enzyme inhibition by two representative pesticides, aldicarb (carbamate) and methyl parathion (OP). Aldicarb was detected with a detection limit of 11 ppb, while methyl parathion¿s detection limit was 18 ppb. This performance is compatible with existing MCLs (maximum contaminant limits) set by EPA. Biosensors which can be taken into the fields will enable cost effective environmental monitoring of water supplies. Pesticide contamination could represent a growing and currently under-regulated threat, since these toxic chemicals are used extensively in agriculture. Potential pollution sources include rainwater runoff of mobile pesticides and spray drift during aerial applications. The proposed sensor will offer a cost reduction strategy for pesticide screening. Prior field screening of samples could contain costs associated with laboratory testing by providing a means to screen out negative, or pesticide free samples.